/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the HISP project nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.webapi.controller;

import io.prometheus.client.CollectorRegistry;
import io.prometheus.client.exporter.common.TextFormat;
import java.io.IOException;
import java.io.StringWriter;
import java.io.UncheckedIOException;
import java.io.Writer;
import org.hisp.dhis.common.DhisApiVersion;
import org.hisp.dhis.common.OpenApi;
import org.hisp.dhis.webapi.mvc.annotation.ApiVersion;
import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * @author Luciano Fiandesio
 */
@OpenApi.Document(domain = Server.class)
@Profile("!test")
@Controller
@ApiVersion({DhisApiVersion.DEFAULT, DhisApiVersion.ALL})
public class PrometheusScrapeEndpointController {
  private final CollectorRegistry collectorRegistry;

  public PrometheusScrapeEndpointController(CollectorRegistry collectorRegistry) {
    this.collectorRegistry = collectorRegistry;
  }

  @GetMapping(value = "/metrics", produces = TextFormat.CONTENT_TYPE_004)
  @ResponseBody
  public String scrape() {
    try {
      Writer writer = new StringWriter();
      TextFormat.write004(writer, this.collectorRegistry.metricFamilySamples());
      return writer.toString();
    } catch (IOException ex) {
      // This never happens since StringWriter::write() doesn't throw
      // IOException

      throw new UncheckedIOException("Writing metrics failed", ex);
    }
  }
}
